The present invention relates to a motor, a method of fabricating a motor and a rotary body apparatus, further in details, relates to a motor capable of solidly supporting a stator coil with high rigidity and having small vibration and noise, a method of fabricating a motor and a rotary body apparatus.
Conventionally, in a rotary body apparatus such as a rotary polygonal face mirror apparatus of a laser beam printer or the like or HDD (hard disk drive), there is used a motor as shown by FIG. 7.
The motor shown by FIG. 7 is provided with a base 110 having a fitting portion (supporting member) 110a projected in a circular ring shape, a hub shaft 130 extended with a shaft 131 from the center of a hub 132 in a circular disk shape and a bearing ring 152 fixedly attached to a lower end portion of the shaft 131.
The bearing ring 152 is inserted into the fitting portion 110a of the base 110, thereby, the hub shaft 130 is rotatably supported by the base 110.
A circular ring portion 133 is extended from a peripheral edge portion of the hub shaft 130 in a lower direction and a rotor magnet 160 is fixed to an inner peripheral wall of the circular ring portion 133.
A stator coil 140 is fixed to an outer peripheral face of the fitting portion 110a.
As shown by FIG. 8, the stator coil 140 comprises a sheet-like yoke 141 laminated with a single or a plurality of sheets having the same shape and coils 142 formed by winding lead wires at the yoke 141. The yoke 141 comprises a mounting portion in a circular ring shape and a plurality of winding portions extended from the mounting portion outwardly in the diameter direction and is fixed to the fitting portion 110a by inserting the fitting portion 110a to a hollow portion of the mounting portion. The coil 142 is formed by winding lead wires around the winding portion.
Further, rotary magnetic field is formed by the stator coil 140 and the rotor magnet 160 is urged by the rotary magnetic field to thereby rotate the hub shaft 130.
The base 110 is fixed to a chassis of a main body apparatus of a printer or HDD.
Such a motor is used in a quiet place such as an office building or the like and therefore, it is requested to restrain vibration as less as possible and prevent noise from being emitted in driving to rotate the motor. Further, particularly in HDD, by high density formation of a hard disk in recent years, fineness is requested in a position of reading data by a magnetic head and also in this regard, there is requested a motor restraining vibration as less as possible, providing high rigidity and rotating with excellent rotational accuracy.
As a method of restraining vibration, there is conceived a technology of forming the fitting portion 110a projected from the base 110 separately and fixing the fitting portion 110a by adhering or fitting. According to the technology, vibration from the stator coil 140 is transmitted to the base 110 after having been attenuated and accordingly, vibration from the stator coil 140 is reduced.
Now, according to the conventional motor, mentioned above, either of an outer peripheral face of the fitting portion 110a provided to the base 110 (both of the fitting portion 110a integrated to the base 110 and the fitting portion 110a separately fixed thereto) and an inner peripheral face of the mounting portion of the yoke is provided with a sectional shape in view from the axial direction in a circular shape. The reason is that the shape is suitable for lathe machining since machining of the fitting portion or the yoke is carried out by the lathe machining and the integrating performance of the stator of the motor for supporting the rotor portion (hub shaft) is excellent.
Further, in order to accurately rotate the rotor portion, there is needed high durability against load applied in high speed rotation and accordingly, in any case, it is necessary to machine to form these parts with excellent roundness and to fit and fix these parts.
However, actually, by influence of chucking in a lathe, it is not possible to machine either of the outer peripheral face of the fitting portion and the inner peripheral face of the mounting portion of the yoke such that sections of these become completely round (complete roundness) and actually, these parts are machined in a irregular circle including the roundness.
Further, when the fitting portion having the outer peripheral face of such an irregular circular shape, is mounted with the mounting portion of the yoke similarly having an irregular circular shape, face contact is not constituted, and in either of the circumferential direction and the axial direction, there is brought about a state in which contact portions and separated portions are irregularly arranged.
Therefore, there are produced portions where external force is received by gaps, the rigidity is deteriorated and when the motor is driven to rotate, the motor is liable to deviate by load of rotation to thereby cause an increase in vibration and noise. Further, the deviation is difficult to deal with since the deviation is caused irregularly.